title: Validity of self-reported utilization of physician services: a population study.
abstract: BACKGROUND
  Health care utilization is of central interest in epidemiology, and most of the studies rely on self-report. The objectives of this study were to assess the validity of self-reported utilization of general practitioner and specialist physician by correlating self-reported utilization with registered services utilization, and to determine the factors related to that validity.
  
  
  METHODS
  The 1997 Belgian National Health Interview Survey (BNHIS) was linked with registered medical utilization data provided by the Belgian Health Insurance Funds. Valid information on general practitioner and specialist physician utilization during the past 2 months was found for 5869 participants at the BNHIS who were aged ≥25 years. Intra-class correlation coefficients were used to determine the rate of agreement, and multinomial logistic regression to model factors influencing under- and over-reporting.
  
  
  RESULTS
  The results demonstrated a substantial agreement between the self-reported and registered general practitioner contacts, and only a minor bias was found towards under-reporting. There was no significant difference between mean self-reported and registered specialist physician utilization, but the agreement was rather moderate. Gender, age, country of birth, self-rated health, number of chronic illnesses, having functional limitations and having mental health problems, were associated with under- and/or over-reporting.
  
  
  CONCLUSIONS
  Studies that aim to compare the utilization of different socio-demographic groups have to take into account that the reporting errors vary by respondents characteristics.
authors.affiliation: 1 Department of Family Medicine and Primary Health Care, Ghent University, Campus Heymans - 6K3, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Peersman
authors.forename: Inge
authors.initials: I
authors.lastname: Pasteels
authors.forename: Dirk
authors.initials: D
authors.lastname: Cambier
authors.forename: Jan
authors.initials: J
authors.lastname: De Maeseneer
authors.forename: Sara
authors.initials: S
authors.lastname: Willems
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001530:Belgium / Q000453:epidemiology; D002908:Chronic Disease / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D058005:General Practitioners / Q000706:statistics & numerical data; D019538:Health Care Surveys; D006304:Health Status; D006801:Humans; D008297:Male; D008511:Medicine / Q000706:statistics & numerical data; D008875:Middle Aged; D010820:Physicians / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D057566:Self Report; D012737:Sex Factors